A system of celestial coordinates with its origin at a specific point on Earth's surface. Usually, the difference
in the position of an object in the sky measured using topocentric and geocentric (Earth-centered) coordinates is very small
because most celestial objects are so far away. The Moon's position, however, can vary as much as 2° depending on where on
Earth it is measured from, and, within the past few years, an observatory in Australia missed spotting an asteroid that passed
close to Earth because it used geocentric rather than topocentric positions.
Topocentric Positions of Major Solar System Objects and Bright Stars
Be sure to read the Notes section (on this page beyond the two forms) for definitions and additional details on the data.